U.S. Pat. Nos. 4,668,721; 4,782,105; 4,876,300 and 4,898,901 describe hydroxylamine compounds, which are structurally distinct from the instant compounds, as process stabilizers for polymeric compositions.
U.S. Pat. No. 4,316,996 teaches 1-hydroxy-2,6-dialkylpiperidines a effective in preventing the discoloration of phenolic antioxidants.
1-Hydroxy-2,2,6,6-tetramethyl-4-piperidone ketals and 1-hydroxy-2,2,6,6-tetramethylpiperidine derivatives are known as effective light stabilizers, but these materials are not known as being effective process stabilizers. Said compounds are structurally distinct from the instant compounds.
1-Hydroxy-2,6-diaryl-4-acyloxypiperidines are described in copending U.S. patent application Ser. No. 696,695.
The instant 1-hydroxy2,6-diaryl-4-piperidone ketal derivatives are novel and are not described or suggested in the prior art.